Treatment for improving cellulose insulation

ABSTRACT

A method for manufacturing a fire retardant cellulose insulation with reduced density and reduced settling. The method consists of adding a material, the fibers of which have a positive electrostatic charge, onto a shredded newspaper base either before or after the addition of a pre-coat, consisting of a mixture of limestone and an antistat. A fire retardant agent is then added and the materials are ground in a finish mill. The newspaper fibers become positioned at an angle to the paper pieces, increasing the distance between the paper pieces, thereby lowering the density of the cellulose. Fibers such as ground cardboard, wood mulch, sawdust, fiberglass fibers and polyester fibers are examples of materials with electrostatically positively charged fibers.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. Ser. No.09/939,178, filed Aug. 24, 2001.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

[0002] (Not Applicable)

REFERENCE TO AN APPENDIX”

[0003] (Not Applicable)

BACKGROUND OF THE INVENTION

[0004] 1. Field of the Invention

[0005] This invention relates generally to cellulose insulation of thetype utilizing a shredded newspaper base which is treated with a fireretardant chemical composition and used for the thermal insulation ofhomes and other building structures. More particularly, the inventionrelates to the addition of a specific range of antistat andelectrostatically positively charged fibrous materials to the newspaperbase which will lower density and reduce settling of the insulation.

[0006] 2. Description of the Related Art

[0007] The manufacture of cellulosic insulation, in accordance with thepresent state of the art, begins with a grinding operation in whichnewspapers are shredded to a level of approximately 1″×1″ pieces andindividual fibers. These fibers and paper pieces, carried in air stream,are then ground in a second operation in which finely ground fireretardant chemical is added to the paper and paper pieces.

[0008] The key to the understanding of the underlying basis of celluloseinsulation is to recognize that cellulose insulation is made up ofnewspaper pieces and fibers which are affected by static electricity.Like elements will repel; unlike elements will attract. A method ofdetermining the electrostatic charge of a material piece or fiber is torub the flat side of a nylon toothbrush about 50 times on a piece ofwool. Then attempt to attract the material in question with the flatside of the toothbrush. If the material is positively charged, it willattach to the flat part of the toothbrush. If the material is negativelycharged, it will not be attracted. Based on the above system, the faceof a newsprint paper piece is positively charged and the edge fibers arenegatively charged. The newspaper separate fibers are also negativelycharged.

[0009] U.S. Pat. No. 4,468,336 refers to an insulation “wherein theloose fill cellulose insulation has a settled density on the order ofabout 2.5 pounds per cubic foot before mixing with staple fibers, andthe mixture of cellulosic insulation with from 2% to 25% by weightstaple fibers has a settled density in the order from 2.1 pounds percubic foot to about 1.1 pounds per cubic foot”. Staple fibers weredefined as acrylic, polypropylene, acetate etc. These fibers areelectrostatically positively charged.

[0010] Because the paper pieces were positively charged, the surface ofthe paper piece attracted negatively charged paper fibers, essentiallyparallel to the face of the paper piece. This attraction caused thepaper piece to become neutrally charged and therefore, no longerstatically attractive. Therefore, the positively charged staple fibersattracted most of the remainder of negatively charged paper fibers,forming a phase separate from the paper pieces. This separate phase isnot settling stable because this structure is not supported by the paperpieces and will condense. It took a large amount of the staple fibers tolower the cellulose density by producing a separate, lower density,paper fiber to positively charged fiber structure.

BRIEF SUMMARY OF THE INVENTION

[0011] In an attempt to improve settling and density of celluloseinsulation, I determined that there was an advantage to produce aspecific type of fiber-paper piece structure. In this structure, use ofthe limestone-antistat mixture as described in U.S. Pat. Nos. 5,399,375and 5,455,065 reduces the static charge on the paper pieces and fibersto a level where fire retardant chemical will adhere to both the paperpieces and fibers. The preferred structure is where the fibers areattached to the paper piece at an angle to the face of the paper piece,not parallel to the face of the paper piece. In this preferredstructure, there are very little separate fiber to fiber groupings.

[0012] Electrostatically, positively charged fibers, such as wood,fiberglass or polyester added either before or after the addition of theantistat to the partially ground paper, are attracted to the negativeedges of the electrostatically charged paper piece. The attachedpositively charged fibers then attract the negatively charged paperfibers, producing a reinforced structure which reduces density andsettling.

[0013] These improvements in density result from the fact that thenegative fibers are deposited at an angle to the face of the paperpiece. The amount of electrostatically positively charged fibers addedwill vary with the type of fiber used. The key is that the amount ofseparate, positively charged fibers to negatively charged fibergroupings is held to a minimum.

[0014] Additional reduction in settling occurs by increasing the amountof antistat beyond that amount necessary to produce lower density.Ultimate settling stability is achieved by reducing the static chargesin the cellulose to the point where the cellulose charges are almostneutral. In achieving this reduction in settling, density is increasedslightly because the electrostatic charges keeping the fibers and paperpieces apart are reduced. Lowering in settling can be accomplished bythe addition of water to the cellulose prior to application, but thelevel of settling increases once the water evaporates.

[0015] The following convention will be used. Newspaper pieces, woodfibers, cardboard fibers, fiberglass fibers and polyester fibers arepositively charged. Newspaper fibers and cardboard pieces are negativelycharged. The relationship of the positively charged fibers to thenegatively charged paper fibers can only be understood by using a highpowered microscope.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0016] There are no drawings.

[0017] In describing the preferred embodiment of the invention, which isillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific term so selected and it is to be understoodthat each specific term includes all technical equivalents which operatein a similar manner to accomplish a similar purpose.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The amount of wood fiber necessary to reinforce the paperpiece/paper fiber structure is in the range of 2% to 8% of the weight ofthe paper and positive electrostatic fiber input. The amount offiberglass fiber and polyester fiber to reinforce the settling stablestructure is in the range of 0.5% to 2% of the paper and positiveelectrostatic fiber input. The preferred amount of electrostaticpositively charged reinforcing fibers is determined by the structureachieved, as seen using a high powered microscope.

[0019] To reduce density, the anti-static constituent of the precoatmixture of anti-stat and finely ground limestone is preferably on theorder of 0.001% to 0.002% by weight of the sum of the paper and positiveelectrostatic fiber input. Above this level, there will be a slightincrease in density of the cellulose. The limestone component range is1% to 2% of the weight of paper and positive electrostatic fiber input.Other fine ground additives may be used in place of the limestone, butfire retardancy will be decreased. This range of anti-stat reduces thestatic charges of the paper pieces, paper fibers and electrostaticallypositively charged fibers so that positively charged fine ground fireretardant chemicals will adhere to the paper pieces, paper fibers andelectrostatically positively charged fibers.

[0020] Since settling reduction is the result of reducing the staticcharges in the system to almost neutral. Settling will significantlydecrease by increasing the amount of anti-static constituent to a rangeof 0.002% to 0.01% by weight of the sum of the paper and positiveelectrostatic fiber input. However, because the fibers and paper piecesare not as far apart because of the additional antistat, density willslightly increase when antistat is raised beyond that of the 0.001% to0.002% anti-stat range.

EXAMPLE 1

[0021] A trial was made using 95% newspaper and 5% cardboard. Thenewspaper was ground in a shredder to a size of about 1″×1″. A precoatmixture was then added to the shredded newspaper, the precoat containingdimethyl distearyl ammonium chloride in the amount of 0.0015% by weightof the sum of the paper and positive electrostatic fiber input, combinedwith limestone in the amount of 1.5% of the weight of paper and positiveelectrostatic fiber input. Partially ground cardboard in the amount of5% of the weight of paper and positive electrostatic fiber input wasthen added. These materials were fed in an air stream into a finish millalong with 10% of a finely ground fire retardant chemical, based on thetotal weight of the system.

[0022] The initial material had a density of 0.70 lbs/cu.ft. Thismaterial was placed in a 12″×12″×6″ high cardboard box in an atmosphereof 50% relative humidity and 70 degrees F. for a period of one month.Settling was 9% after one month.

[0023] Commercial cellulose, not containing the cardboard or antistat,under the same conditions as above, had an initial density of 1.3lb/cu.ft and settled 16% over the same period.

EXAMPLE 2

[0024] A trial was made similar to Example 1 but the cardboard was firstcombined with the newspaper base before the addition of the limestoneantistat mixture. Under conditions similar to Example 1. Settling after30 days was 10% after one month and initial density was 0.70 lb./cu. ft.

EXAMPLE 3

[0025] A trial was made similar to Example 1 using 5% cardboard but theantistat was increased to 0.004% of the weight of paper and positiveelectrostatic fiber input. The initial material density increased to0.80 lbs./cu.ft. This material was placed in a 12″×12″×6″ high box in anatmosphere of 50% relative humidity and 70 degrees F. for a period ofone month. Settling was 3% after one month.

EXAMPLE 4

[0026] A trial was made similar to Example 1 but the antistat wasincreased to 0.008% of the weight of paper and electrostatic fiberinput. The initial material density increased to 0.89 lbs/cu.ft. Thismaterial was placed in a 12″×12″×6″ high box in an atmosphere of 50%relative humidity and 70 degrees F. for a period of one month. Settlingwas 2% after one month.

EXAMPLE 5

[0027] A trial was made similar to Example one but 5% sawdust wassubstituted for the cardboard. Anti-stat was added at 0.004% of theweight of paper and electrostatic fiber. The initial material densitywas 0.80 lbs/cu.ft. This material was placed in a 12″×12″×6″ high box inan atmosphere of 50% relative humidity and 70 degrees F. for a period ofone month. Settling was 3% after one month.

EXAMPLE 6

[0028] A trial was made similar to Example 1 but 2% fiberglass wassubstituted for the cardboard used in Example 1. Under conditionssimilar to Example 1, settling after 30 days was 10% and density was0.75 lb./cu. ft.

EXAMPLE 7

[0029] A trial was made similar to Example 1 but 1% polyester fiberswere substituted for the cardboard used in Example 1. Under conditionssimilar to Example 1, settling after 30 days was 8% and density was 0.781b/cu. ft.

EXAMPLE 8

[0030] A trial was made similar to Example 2 but 1% polyester fiberswere substituted for the cardboard used in Example 2. Under conditionssimilar to Example 2, settling after 30 days was 12% and density was0.77 lb/cu. ft.

[0031] While certain preferred embodiments of the present invention havebeen disclosed in detail, it is to be understood that variousmodifications may be adopted without departing from the spirit of theinvention or scope of the following claims.

1. An improved cellulosic insulation having reduced density and settlingcomprising (a) shredded cellulosic fibers and paper pieces which areprecoated with a mixture of limestone and an antistatic agent eitherbefore or after the addition of (b) electrostatically positively chargedfibers and (c) fire retardant chemicals which are adhered on saidshredded cellulosic fibers, electrostatically positively charged fibersand paper pieces.
 2. An insulation in accordance with claim 1 whereinsaid anti-static agent is a quaternary ammonium compound.
 3. Aninsulation in accordance with claim 1, wherein said insulation comprisessubstantially 0.001% to 0.01% by weight of said antistatic agent, basedon the weight of cellulosic fibers, paper pieces and positiveelectrostatic fiber input.
 4. An insulation in accordance with claim 1,wherein said mixture of antistat and limestone comprises substantially1% to 2% of the weight of cellulosic fibers, paper pieces andelectrostatic positively charged fibers.
 5. An insulation in accordancewith claim 1, wherein said insulation comprises positively chargedelectrostatic fibers such as wood fibers, shredded cardboard, wood mulchand sawdust at a level of substantially 2% to 8% of the weight ofcellulosic fibers, paper pieces and electrostatic positively chargedfibers.
 6. An insulation in accordance with claim 1, wherein saidinsulation comprises positively charged electrostatic fibers such asfiberglass or polyester fibers at a level of substantially 0.5% to 2% ofthe weight of cellulosic fibers, paper pieces and electrostaticpositively charged fibers.
 7. An insulation in accordance with claim 1,wherein the electrostatically negative paper fibers are angledpredominantly from about 15% to perpendicular to the surface of thepaper pieces.
 8. A method for manufacturing fire retardant cellulosicinsulation of the type comprising shredded cellulosic fibers precoatedwith a mixture of limestone and an antistatic agent and having a fireretardant agent deposited on it wherein the improvement comprises addinga positively charged electrostatic fiber either before or after theaddition of the mixture of limestone and an antistatic agent.
 9. Amethod in accordance with claim 8, wherein positively chargedelectrostatic fibers such as ground cardboard, wood mulch, and sawdustare added in the amount of substantially 2% to 8% of the weight of thecellulosic fibers, paper pieces and electrostatic positively chargedfibers.
 10. A method in accordance with claim 8, wherein positivelycharged electrostatic fibers such as fiberglass or polyester are addedsubstantially in the amount of 0.5% to 2% of the weight of cellulosicfiber, paper pieces and electrostatic positively charged fibers.